In Japan, it is planned to completely shift television broadcasting to terrestrial digital broadcasting. A feature of the terrestrial digital broadcasting is simple motion picture broadcasting for a mobile terminal device. The simple motion picture broadcasting delivers an image via one particular segment among 13 segments divided from a band of one channel (6 MHz) assigned to each broadcasting station.
At present, cellular telephone devices and the like, which are equipped with features (compatible antenna, tuner, signal processing unit, etc.) compatible with such terrestrial digital broadcasting, and which are capable of playing a variety of information received from the terrestrial digital broadcasting, are being introduced.
Here, such a cellular telephone device equipped with a function to receive the terrestrial digital broadcasting is designed such that, while television broadcasting is being received and watched via an antenna for receiving the terrestrial digital broadcasting, communication (for example, data communication by a CDMA (code division multiple access) method) can be performed via another antenna at the same time.
Moreover, a UHF band of 470 MHz to 770 MHz is assigned as a frequency bandwidth of the terrestrial digital broadcasting; on the other hand, a frequency bandwidth to a higher frequency side than the frequency bandwidth of the terrestrial digital broadcasting is assigned as a transmission/reception frequency bandwidth of the data communication by the CDMA method.
Incidentally, in a case in which the high frequency band (770 MHz) of the terrestrial digital broadcasting and the low frequency band of the CDMA communication method fall within a certain range, and when data is transmitted and received by the CDMA communication method while watching the terrestrial digital broadcasting, a signal of the CDMA communication method may work as an interfering wave, thereby making it difficult to watch the terrestrial digital broadcasting in some cases. Alternatively, conversely, a broadcast signal of the terrestrial digital broadcasting may work as an interfering wave, thereby making it difficult to perform data communication by the CDMA communication method in some cases.
Here, in Patent Document 1, by designing a frequency bandwidth of the terrestrial digital broadcasting to be narrow, only a desired channel signal is extracted, the reception sensitivity is improved, and it is not affected by a frequency band of another antenna; and it is conceivable, for example, to utilize such a technique in a case in which data communication is performed by the CDMA method while receiving the terrestrial digital broadcasting.
Patent Publication 1: Japanese Unexamined Patent Application, First Publication No. 2007-104495